1. Field of the Invention
This invention relates to the application of lubricant to the moulds--in particular the blank moulds--of a hollow glassware forming machine while the machine is operating. (Although certain features embraced within this invention, but inventive in their own rights, could be used in lubrication of other moulds).
Glass bottles and jars are made by a blow moulding process. A gob of molten glass is introduced into a so-called blank mould and formed to a desired hollow shape by pushing a solid core into the glass or applying an air jet to achieve the same result. The hollow parison formed in this way is then transferred from the blank mould to a finish or blow mould in which it is blown out to the shape of the finished bottle or jar.
The most commonly used machine for this purpose is a so-called Independent Section (IS) machine having six, eight or ten sections each of which has a blank mould and a blow mould. The machine takes its name from the fact that any section can be stopped while the others continue to run. This facility is employed when blank moulds are changed. The moulds of each section may have one, two or three cavities each of which will be charged with glass simultaneously and the machines are accordingly classified as single gob, double gob or triple gob IS machines.
The moulds of glass forming machines require lubrication at regular intervals. In the case of blank moulds this is typically in the order of every 15 minutes or so. Customarily the lubricant consists of a suspension of graphite in a liquid carrier which consists predominantly of oil. The application of the lubricant to the moulds has for many years been done by hand, using a small mop; and is termed swabbing.
This is so despite the risk to which the machine operator is exposed; moreover hand swabbing makes the extent of lubrication inherently unrepeatable, because it is dependent on the individual operator.
2. Summary of the Prior Art
It has been appreciated for years that it would be desirable to have mechanical, and preferably automatic, equipment for the application of lubricant to moulds of glass forming machines.
There have been a number of proposals for solving the problem. Most of these have entailed applying lubricant by spraying. Many have suggested spraying the lubricant into the mould cavities while the moulds are closed, an approach which does avoid accumulating lubricant on the mating faces of the moulds so that they cannot close properly. Examples of this approach are U.S. Pat. Nos. 3,141,752; 3,480,422; 3,623,856; 3,721,542; and 3,814,594; and UK Pat. No. 1,371,728.
U.S. Pat. No. 3,523,016 proposes applying a spray of lubricant to the open blank mould halves. The spray is discharged from nozzles mounted on the neck ring arm (this carries rings which mould the necks of containers, and convey the formed parisons to the blow mould). The spray is discharged as the arm passes between the open mould halves. An airless spray is employed.
U.S. Pat. No. 3,141,752, (which is directed to apparatus which sprays while the mould is closed) mentions earlier attempts using fixed sprays which discharged while the moulds were open. It is stated, however, that this required the glass forming machine to be slowed down, and did not reliably give a uniform application of lubricant. Those proposals are also mentioned in U.S. Pat. Nos. 3,623,856 and 3,814,595.
The prior proposals have displayed various disadvantages. Some entail substantial modification to an IS machine. Some cause a loss of ware, i.e. the next glassware moulded is spoilt (which also happens with hand swabbing). Loss of ware can even continue for two or three moulding cycles.
It has been reported that apparatus has run satisfactorily for three months or so, but has then required an excessive amount of work to keep it running thereafter.
However, for whatever reasons, no automatic swabbing equipment has gained commercial acceptance and hand swabbing remains widespread.